Golf ball cover



Jan." 1o, 1939.

R. A. CRAWFORD 2,143,544

GOLF BALL COVER Filed Oct. 8, 1936` Q f ZZ-z L/EWDL. 'EraaaaJi-C'Eazuymd4 Patented Jon. 10,1939

PATENT OFFICE 2,143,544 com BALI. covEa Richard A. Crawford, Akron,Ohio, assignor to The B..F. Goodrich Company, New York, N. Y., a.corporation of New York y Application October 8,` 1936, Serial No.104,712

5 claims. (cl. 27a-s2) This invention relates to` improved compositionsuseful in golf ball covers. Its principal object is to make a tough andshock-resistant cover composed only partly of balata without im- 5pairing the exibility, click, and other properties essential' to golfball covers.

Heretofore', the best golf ball covers have been comprised principallyof gutta percha or balata in a vulcanized or unvulcanized state.4 Thesel0. compositions make satisfactory covers,'but theyl are very expensive.`Cheaper covers in which 'part "of the balatra is replaced byrothersubstances such asglue or'llers have been developed, but theirproperties were not good enough to displace balata :covers on thefirst-class balls. The substituted balata covers ,were often found to beeither dead or too rubbery, tolack click, or to lack toughness sothatthey became dented or" gouged outunder the severe shocks to ywhich golfballs arenecessarhy subjected. j

I have Adiscovered ,a golfy ball cover composition` comprising a threecomponent system of masticated rubber, refined balata, and thermoprene,which system substantially duplicates .the me- The most important factorin my invention is that the three components mustibe present in suchproportions as to form a stable system. Stability is defined throughoutlthis application sharply (180). A stable system shows no whitening atthe bend. Unstable system whiten, and if suiliciently unstable,'willcrack. Unstable 4systems are unsuitable for golf ball covers becausethey are apt to be spongy or cheesy, and present a surface which iseasilyv dented and cut. But stable systems of the three components whichI employ exhibit properties` similai` to and sometimes better than theproperties of the best balata covers which are manufactured. y

- The invention is illustrated by the accompanywith and having lessunsaturationthan rubber.l

5o-A s examples of suitable thermoprenes, ll will Vmention those` madeaccording to the specifica` tions of UI'S. Patent No. 1,605,180 grantedNovenxber 2, 1926, vto Harry L. Fisher. `I preferA to the harder, tough,heat-plastic products which more or less resemble balata.

chanlcal properties of wholly deresinated balata.v

by the following test: A molded sample is bent To prepare thermoprene, Iprefer to proceed as-in Example 2 of aforementioned Patent No. 1,605,180except that I use 8 parts of P-phenol sulfonic acid. I may use any ofthe equivalents for p-phenol sulfonic acid mentioned in the patent,however. Y To prepare another thermoprene useful for golf-ball covers, Iisomerlze parts by Weight` of specially selected pale crepe by adding 'lparts of sulfuric acid (sp. gr.' 1.84) and one part by weight of retortpine tar or turpentine and heating until a balata-like product isformed.

Using one of these thermoprenes, I prepare my golf ball cover stocks. Ipreferably use rened' balata and high grade mastlcated pale crepe. Onevery satisfactory material comprises:

y v Parts by weight Refined balata 53 Masticated rubber 27 Thermoprene20 The thermoprene mentioned in these two recipes may be made fromrubber isomerized with either p-phenol sulfonic acid or sulfuric acid.Resilience, hardness, and resistance to cut may be varied by changingthe relative proportions of the three components. Stable compositionssuitable for use as golf ballk cover compositions -will Any type of golfball center is then covered with the stock in any desired manner, andthe ball is subjected to heat and pressure to bind the cover to thecenter and to set the cover into a hard, durable material. A preferredmethod is to use a center comprising a liquid core surrounded by awinding of tense rubber thread. The cover stock is shaped into twohemispheres, usually with the aid of heat. The hemispheres are placedaround the center, and the ball is placed in a heated press and cooledunder pres sure.

A variety of materialsmay be added to these stable three-component'stcksto vary the propbe found within the following range of proportions: 1

Parts by weight Refined balata 25 to '15 Masticated rubber 12 to 50Thermoprene 15 to 50 erties of the covers. An excellent white cover ismade by the following recipe:

Parts by' weight Rened balata 39.80 Masticated rubber- 17.05 Thermoprene21.05 'Iitanium dioxide 22.00 Ultramarine blue .10

The thermoprene may be made from rubber isomerized with either sulfuricacid or p-phenol sulfonic acid. A ball with this cover has a long life,gives good click, and the cover is unusually resistant to severe shockssuch as are produced when the ball is topped."

If a vulcanized cover is desired, curing ingredients may be added. Thethermoprene in the following recipes is made from rubber and para phenolsulfonic acid.

To prepare the cover, equal portions of these two recipes are mixed justbefore the stock is to be used. After the stock has been applied to thecenter, the ball is cured in a press for ten minutes at 240 F.

All recipes have to be prepared with a. particular thermoprene in mind.Although it often happens that thermoprenes prepared by diierentisomerizing agents may be substituted in the same recipe, differentthermoprenes have diierent phase relationships with rubber and balata.The conditions of stability for each thermoprene must be determinedbefore recipes containing the thermoprene are prepared.

It is to be understood that my invention is not limited by the specicexamples herein cited for illustrative purposes. It is the essense of myinvention to form a stable system comprising at least rubber,thermoprene and balata. As long as stability is maintained, proportionsmay be altered, and pigments, llers, softeners, accelerators,antioxidants, and the like may be incorporated into the covers withoutexceeding the spirit and scope of my invention.

I claim: f

1. A golf ball cover comprising balata, a thermoprene, and rubber insuch proportions as to form a stable system.

2. A golf ball cover comprising balata, rubber isomerized with sulfuricacid, and rubber in such proportions as to form a stable system.

3. A golf ball cover comprising balata, rubber isomerized with p-phenolsulfonic acid, and rubber in such proportions as to form a stablesystem.

4. A golf ball cover comprising a stable system of balata, athermoprene, rubber, and curing agents.

5. A golf ball cover comprising a stable system of balata, rubberisomerized with p-phenol sulfonic acid, rubber, sulfur, and anaccelerator.

RICHARD A. CRAWFORD.

